1. Field of the Invention
The present invention relates to a superconductivity rotor having a torque tube, and more particularly, to an improvement of a torque tube provided in the superconductivity rotor.
2. Description of the Prior Art
In general, a superconductivity rotor using a superconductivity wire instead of copper wire comprises, as shown in FIG. 1, a field coil portion 10 wound with a superconductivity wire so as to generate a high magnetic field, a support portion 20 for supporting the field coil portion 10 and torque tubes 30 positioned at both ends of the support portion 20 and transmitting a torque to an outside from the field coil portion 10. The field coil portion 10 and the support portion 20 are received in an inner casing 40. The inner casing 40 and the torque tube 30 are received in an outer casing 50.
In addition, one side of the outer casing 50 is formed with a shaft 51 to which load is applied and the other side of the outer casing 50 is formed with an end part 52 connecting with a cooling device.
In the conventional superconductivity rotor having the above structure, the torque tube 30 serves to transmit a torque generated from the support portion 20 to the outer casing 50, in case of a motor, and also serves to transmit a torque applied from the outer casing 50 to the support portion 20, in case of a generator.
The torque tube 30 also serves to minimize heat transfer between the support portion 20 under very low temperature and the outer casing 50 of the superconductivity rotor under room temperature.
In the mean time, the torque tube 30 is formed into a hollow cylindrical shape. Accordingly, the torque tube 30 has only an effect of transmitting the torque and minimizing the heat transfer with the outer casing 50. As a result, it cannot cope with shrinkage occurring in a shaft direction (vertical direction in the drawing).
In addition, the torque tube 30 should be lengthened so as to minimize the heat transfer, so that an overall length of the rotor becomes longer.